Uso da lignina recuperada como coagulante no tratamento de efluente

Abstract

Residual water treatment techniques have been improved in search of viability, efficiency and sustainability. Based on this conception, it is opportune to use and recover an organic coagulant biopolymer from the residue of a paper and cellulose industry, and that the use of this recovered material presented coagulation capacity in the effluent treatment process. It is possible to introduce the organic coagulant in order to reduce the inorganic coagulant based on metal, since the use of aluminum sulfate results in a residue that is deposited in the human body, which corroborates with Alzheimer's disease. This is a work that had the objective of recovering lignin from black liquor, evaluating the results obtained from lignin recovery, comparing the post-treatment ecotoxicity of lignin and aluminum sulfate, being coagulating agents, and to define the best dosage for the observed organic coagulant. The experiments were carried out in the Jar-Test device, using the inspiration and sedimentation times found in the literature for this process, and the raw effluent sample was treated with dosages of 8, 12 and 16 mL of coagulant, and with the defined pH for each coagulant. The results for the recovery of lignin were 2.8 g for each 5 mL of black liquor sample, with thermoanalysis test by gravimetry (TGA) to prove that the recovered material had lignin. The evolution of the lignin recovered in the Jar-Test test showed important results, with a reduction in turbidity, true color, chemical oxygen demand and biochemical oxygen demand, reaching percentages of 96,9, 98,6, 96,9 and 99,7, respectively. Along with this reduction, lignin did not present a toxic characteristic to the living organism studied, Artemia salina L., and aluminum sulfate proved to be toxic to the same bioindicator.